Insulating liner for man-carrying buckets

ABSTRACT

A man-carrying bucket for utility trucks in which a man is elevated in the bucket to work on electric powerlines, lamps and the like. The bucket is constructed of molded plastic reinforced with fiberglass and is additionally insulated by a polyethylene liner that is constructed in three pieces, a main portion covering the sidewalls and bottom of the bucket, a top portion that extends up over the top flange of the bucket, and a bottom portion additionally protecting the floor of the bucket. Economy of manufacture is attained by molding the top and bottom portions as a unitary element and then severing the element to provide the top and bottom portions of the liner. The three-piece construction is advantageous from the standpoint of economy in manufacturing and testing of the bucket, and durability and reliability in service.

United States Patent Valentine 7 Feb. 15,1972

[54] INSULATING LINER FOR MAN- CARRYING BUCKETS Primary Examiner-Reinaldo P. Machado [72] Inventor:

Attorney-Bosworth, Sessions, Herrstrom and Cain Alan T. Valentine, Fairview Park, Ohio [73] Assignee: The Ohio Brass Company, Mansfield, ABSTRACT A man-carrying bucket for utility trucks in which a man is elevated in the bucket to work'on electric powerlines, lamps [22] Filed: Sept. 23, 1970 and the like. The bucket is constructed of molded plastic reinforced with fiberglass and is additionally insulated by a [2i 1 Appl. No.: 74,754

polyethylene liner that is constructed in three pieces, a main portion covering the sidewalls and bottom of the bucket, a top dove eee mmmmmmm me ma m o h n m m fl 0 0 e Yn e mm a w 0 f lm B o ewommk m 6 e n.. H V mmo 4 2 no bm m we mm ed 5mm F j 2 POE Wm w W M '1 lll llilllllllllilllllllllllillrlllllill 0 W w m i \\lbw .m\ Llrli.lwtl\\\\\-li1-i\-.\lri.0 t r .l O .l U H m A" ""p" e un b a mum u e N m m E a 4 bm md 2 Maia? m mm m m w m m nwmm C mm iw 7 mmmmm e m onme md m otmm d h m e .tm a mu mma wa 0 4 ok mn k Z mbc e c I o umwm nwu 1 Pabtifisb l 7 81 222 3 1 000000 1 0 111 7 2 nu n6 mmm 0B2, n Z 2 92 u n 28 u 6 m m M s 2 m n. M E m m m JEv T "n" 6 m1 m A m m m m u u .n P m m m 3 m m C 5 m m m m w E i m u m c T. m u n A mwh e C n u r. T. W53 m n .N S e D MN m R E Tm n 588 mma N mm m U 111 I ll/ L 202 u mun UIF 1]] 1 @MM 2 8 5M5 1,4,4, [f.\[ l 333 PATENTEDFEB 15 I972 INVENTOR.

4444/ 7.- yfllfA/T/A/f Hm I INSULATING LINER FOR MAN-CARRYING BUCKETS BACKGROUND OF THE INVENTION This invention relates to insulated buckets that are mounted on the booms of utility trucks and are employed to elevate linemen to positions where they can work on the installation and repair of electric powerlines, lamps and the like, and more particularly, to insulating liners for buckets constructed of molded plastic reinforced by fiberglass (hereinafter referred to as fiberglass), and to a method of making such liners.

Buckets of this general type are widely used and are ordinarily supported by booms that are constructed of fiberglass or, if not constructed of insulating material, are insulated from the trucks on which the booms are mounted. The insulated buckets and booms enable the linemen to work in safety even on relatively high-voltage lines. The fiberglass buckets are ordinarily square in cross section with a flat bottom. They have a depth of about three feet and a flange at the top and are customarily tested periodically to a specified high voltage such as 100,000 volts DC. However, since tree branches or other obstructions can puncture the buckets and destroy their electrical integrity, it is customary to employ liners composed of an insulating material such as polyethylene within the buckets. l'leretofore, the liners have been molded in one piece and tested by the manufacturer at about 50,000 volts AC. Prior liners have not been entirely satisfactory because of difficulties encountered in manufacturing and testing them and also because of the fact that the vertical depth of the fiberglass buckets and of the liners between the top flanges and the bottoms thereof cannot economically be held to close tolerances and may vary as much as two inches or more, putting a severe strain on the liner if the liner is not as deep as the bucket, and leaving the top flange of the liner unsupported if the liner is deeper than the bucket. The bottoms of the liners are important to protect the fiberglass from damage by the shoes of the linemen and the upper flange is important to provide insulation in this area. If damage occurs to a one-piece liner the entire liner must be replaced.

SUMMARY A general object of the invention is to provide improved liners for buckets such as those described above that will obviate the difficulties noted above. According to a preferred form of the invention this and other objects are attained by providing a conventional fiberglass bucket with a three-piece insulating liner comprising a top member having a flange that extends over the flange of the fiberglass bucket and downwardly extending sidewalls, a main member that has a bottom portion that overlies the bottom of the bucket and sidewalls extending upwardly along the inner surfaces of the walls of the bucket to a zone close to the top of the bucket, and a bottom member that fits within the main member and has walls extending a short distance up the sides of the main member. The sidewalls of the top member telescope with the sidewalls of the main member. According tothe method, the top and bottom members are provided by molding them as a unitary member and then severing this member to provide the top and bottom portions. The bottom member furnishes additional protection for the bottom of the bucket and, as will appear below, is advantageous in the manufacture and testing of the elements ofthe liner.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which illustrate a preferred form of the invention:

FIG. 1 shows a typical utility truck having mounted on it a bucket embodying the invention;

FIG. 2 is an exploded view of the components of the bucket shown in FIG. 1;

FIG. 3 is a vertical sectional view of the assembled bucket; and

FIG. 4 shows the top and bottom liner members at one stage of the manufacturing process.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown somewhat diagrammatically in FIG. 1, a bucket 10 having a liner made in accordance with the present invention is adapted for use with a utility truck 11 which supports a jointed boom 12 that carries the bucket. The truck and boom may be of various known constructions; ordinarily, the boom is hydraulically operated and is controlled by two sets of controls, one being mounted at or adjacent the bucket 10 and the other on the body of the truck. The power for operating the boom is usually hydraulic and is furnished by a power takeoff from the truck engine. These elements may be of known construction and form no part of the present invention.

The bucket 10 is preferably composed of rigid, molded fiberglass; i.e., a plastic such as a polyester reinforced with fiberglass. The bucket is shown herein as being of conventional square cross section but buckets of round or other cross sections may obviously be employed. The bucket is molded in one piece and comprises vertical sidewalls 14, a horizontal bottom 15 and a top flange 16. A bracket 17, shown in broken lines in FIG. 3, is molded integrally with one sidewall 14 of the bucket and provides for conventional attachment of the bucket to the upper end of the boom 12. Typically, the bucket may have a molded wall thickness of about inch, may be about 22 inches square and have a depth from the flange 16 to the bottom 15 of about 3 feet. The flange 16 preferably extends upwardly at a slight angle as shown in FIG. 3 for convenience in molding, and has a width of, for example, 2 inches.

As noted above, buckets of this type are well known; they are tested at the factory to withstand I00 kv. DC with not in excess of a prescribed very small leakage current, and they maintain this dielectric strength in service so long as their structural integrity is not substantially impaired. As noted above, however, fiberglass buckets are subject to serious damage from contact with light poles and other structural members and with tree branches, and from the shoes of the linemen riding in the buckets and from tools used by the linemen.

According to the present invention, the dielectric strength of the bucket assemblies is increased, the interiors of the buckets and the top flanges are protected against damage and the dielectric strength of the complete assemblies is maintained at a safe level in spite of the substantial damage to the fiberglass buckets by means of a liner composed of a tough, flexible insulating material, preferably in the form of molded polyethylene having a thickness-of, for example, 5/l6 inch, although other suitable insulating materials such as rubber may be employed. I

According to a preferred form of the present invention the liner is made up ofa main member 20, a top member 21 and a bottom member 22. The main member has sidewalls 23 formed in a square or other configuration to conform to the interior surfaces of the sidewalls 14 of the fiberglass bucket and a bottom portion 24 that rests upon the bottom 15 of the bucket. The sidewalls and bottom of the member 20 are joined by curved portions 25 that conform to the curved portions 26 of the fiberglass bucket and the sidewalls 23 of the member 20 also intersect in curved portions 28 that conform to the interior curves of the bucket. For ease in handling, fingerholes 29 are provided in the upper portions of two of the walls 23 of the member 20 near the top edge 30 thereof. In the assembled bucket, the walls 23 of the member 20 terminate slightly (for example, an inch or so) below the intersection of the walls 14 of the bucket and the flange 16, as shown in FIG}.

The distance between the top edge 30 of the member 20 and the juncture of the flange 16 with the body of the fiberglass bucket 10 may vary because, as noted above, the vertical dimensions of the buckets and the vertical dimensions of the members 20 may vary substantially due to the nature of the manufacturing processes. However, this is a matter of no consequence with bucket liners made according to the present invention since the flange 16 of the fiberglass bucket is protected by the flanged top liner member 21. Top member 21 has downwardly extending walls providing a portion 31 of square or other cross section that conforms to, telescopes within the extends downwardly for several inches along the upper portion of the main member 20, and a flange portion 32 that overlies and protects the flange 16 of the fiberglass bucket 10. The flange 32 merges into the downwardly extending portion 31 in a curved portion 33 and terminates in a de-. pending outer flange 35. Flange 32 overlies flange 16 and the depending flange 35 protects the particularly vulnerable edge of the flange 16. The flange 35 also assists in protecting the assembly against penetration of moisture between the inner surface of bucket and the outer surface ofthe liner.

The upper member 21 is secured in position by bolts 36 that extend through the horizontal portion 34 of the flange 32 and through registering openings in the flange 16 of the bucket 10. Since the main member 20 and the top member 21 are separately formed, it will be evident that the bottom 24 of the member 20 can be positioned firmly against the bottom of the bucket 10 and the flange 32 of the top member 30 properly aligned with respect to the flange 16 regardless of reasonable variations in the vertical dimensions of the liner members and the bucket.

In order to furnish additional protection for the bottom of the bucket, the bottom member 22 is disposed within the main member 20. The bottom member 22 has a bottom 39 that rests upon the bottom 24 of the main member and has sidewalls 40 that extend a short distance, for example, about 3 inches, upwardly along the walls 23 of the member 20, bottom member 22 being curved at the juncture of the bottom 39 and the walls 40 and the junctures of the walls 40 with each other to conform to the interior of the main member 20, as shown. The bottom and top edges of members 21 and 22 are preferably spaced a substantial distance from each other, as shown. Member 22 is also preferably provided with fingerholes 41 for assistance in handling, inserting or removing the member from the bucket.

It will be evident with this arrangement that double protection is provided for the bottom 15 of the fiberglass bucket by the bottom member 22 and the bottom 24 of the main member 20, and that the flange 16 of the fiberglass bucket is well protected by the flanges 32 and 35 of the top member 21. These members fit correctly regardless of reasonable variations in dimensions of the bucket or the members, and in the event of damage any one of the liner members 20, 21 or 22 that may be damaged can be replaced without the necessity of replacing the entire liner. This efiects substantial saving in service since most of the damage ordinarily occurs to the upper flanged member 21 or to the bottom member 22, these being the smaller, less costly members.

The main member 20 can be manufactured at reasonable cost by conventional molding methods; the manufacture being simplified by the fact that it is not necessary to maintain the vertical dimension of the insert with a high degree of accura cy. Preferably, the main members are electrically tested, before the fingerholes 29 are punched in them, by filling the members with water, disposing them in a bath of conductive liquid such as water slightly shallower than the depth of the member and applying the required voltage, for example, 50,000 volts AC. between the body of water within the member and the body of liquid in the tank surrounding the member and measuring the leakage current which is required not to exceed a specified amount.

According to the present invention, the manufacture of members 21 and 22 can be carried out at reasonable cost and with conventional equipment. This is accomplished by molding these members in one piece toproduce the element 43 shown in FIG. 4 and then the two members 21 and 22 are formed by severing the element 43 along the broken line 44. It will be noted that the total depth of element 43 is substantially less than the total depth of the main member 20. If it is desired to test members 21 and 22, the element 43 is severed after the testing has been completed; thus, by testing the element 43 the two members 21 and 22 can be tested in one operation by the same method described with respect to the member 20; namely, by filling the element 43 with liquid, immersing it in a liquid bath and measuring the leakage current under the specified voltage. Here again, the leakage current must be less than a specified low value under a specified voltage such as 50,000 volts AC. The fingerholes 41 are formed after the testing, if any, has been completed and after element 43 has been severed to form the parts 21 and 22.

From the foregoing description of a preferred form of the invention, it will be evident that the invention provides an improved bucket and liner assembly particularly for man-carrying buckets that are used with electric utility trucks and the like. The liners can be manufactured and installed at reasonable cost in buckets of conventional design, variations in dimensions of the buckets within reasonable tolerances do not affect the fit of the liners within the buckets; the fiberglass buckets are protected particularly well in the areas where they are subject to greatest damage, namely in the areas of the upper flange and the bottoms of the buckets; and, in the event of damage to a liner, it is necessary only to. replace the damaged part of the liner and not the entire liner.

While a particular design of insert adapted for a particular type of bucket is shown herein, it will be evident that the principles of the invention may be adapted to buckets of different shapes and configurations and of different material. The essential characteristics of the invention are summarized in the appended claims.

What is claimed is:

1. A liner for a man-carrying bucket for utility trucks and the like, the bucket having a bottom and sidewalls extending upwardly from the bottom, the liner being composed of insulating material and comprising a main member having a bottom portion adapted to overlie the bottom of the bucket and sidewalls adapted to conform to the sidewalls of the bucket and to extend upwardly along the sidewalls of the bucket and terminate slightly below the top of the bucket, a bottom member having a bottom adapted to rest upon the bottom of the main member and sidewalls adapted to extend upwardly within and conform to the sidewalls of the main member, and a top member having an outwardly extending flange adapted to overlie the top of the bucket and sidewalls adapted to extend downwardly within and conform to the sidewalls of the main member, the downwardly extending sidewalls of the top member terminating short of the upwardly extending sidewalls of the bottom member when the members are installed in a bucket.

2. A liner according to claim 1 in which the members comprising the liner are composed of molded, flexible insulating material.

3. A liner according to claim 1 in which the members comprising the liner are composed of molded polyethylene.

4. A liner according to claim 1 in which the main member and the bottom member have flat bottom portions adapted to conform to the flat bottom of a bucket.

5. A liner according to claim 4 in which the sidewalls of the main member and the bottom member extend vertically upwardly and in which the sidewalls of the top member extend vertically downwardly from the flange thereof.

6. A liner according to claim 1 in which the flange on the top member is adapted to overlie a flange on the bucket and terminates in a downwardly extending flange that is adapted to surround the edge of the flange on the bucket.

7. In combination with a man-carrying bucket for utility trucks and the like, the bucket being composed of fiberglass and having a flat, horizontal bottom, sidewalls extending vertically upwardly from the bottom and an outwardly extending flange atthe top of the sidewalls, a liner composed of molded polyethylene material and comprising a main member having a bottom portion overlying the bottom of the bucket, sidewalls conforming to the sidewalls of the bucket extending upwardly along the sidewalls of the bucket and terminating slightly below the flange at the top of the bucket, a bottom member composed of insulating material and having a bottom resting upon the bottom of the main member and sidewalls extending extending downwardly within and conforming to the sidewalls of the main member, the downwardly extending sidewalls of the top member terminating short of the upwardly extending sidewalls of the bottom member. 

1. A liner for a man-carrying bucket for utility trucks and the like, the bucket having a bottom and sidewalls extending upwardly from the bottom, the liner being composed of insulating material and comprising a main member having a bottom portion adapted to overlie the bottom of the bucket and sidewalls adapted to conform to the sidewalls of the bucket and to extend upwardly along the sidewalls of the bucket and terminate slightly below the top of the bucket, a bottom member having a bottom adapted to rest upon the bottom of the main member and sidewalls adapted to extend upwardly within and conform to the sidewalls of the main member, and a top member having an outwardly extending flange adapteD to overlie the top of the bucket and sidewalls adapted to extend downwardly within and conform to the sidewalls of the main member, the downwardly extending sidewalls of the top member terminating short of the upwardly extending sidewalls of the bottom member when the members are installed in a bucket.
 2. A liner according to claim 1 in which the members comprising the liner are composed of molded, flexible insulating material.
 3. A liner according to claim 1 in which the members comprising the liner are composed of molded polyethylene.
 4. A liner according to claim 1 in which the main member and the bottom member have flat bottom portions adapted to conform to the flat bottom of a bucket.
 5. A liner according to claim 4 in which the sidewalls of the main member and the bottom member extend vertically upwardly and in which the sidewalls of the top member extend vertically downwardly from the flange thereof.
 6. A liner according to claim 1 in which the flange on the top member is adapted to overlie a flange on the bucket and terminates in a downwardly extending flange that is adapted to surround the edge of the flange on the bucket.
 7. In combination with a man-carrying bucket for utility trucks and the like, the bucket being composed of fiberglass and having a flat, horizontal bottom, sidewalls extending vertically upwardly from the bottom and an outwardly extending flange at the top of the sidewalls, a liner composed of molded polyethylene material and comprising a main member having a bottom portion overlying the bottom of the bucket, sidewalls conforming to the sidewalls of the bucket extending upwardly along the sidewalls of the bucket and terminating slightly below the flange at the top of the bucket, a bottom member composed of insulating material and having a bottom resting upon the bottom of the main member and sidewalls extending upwardly within and conforming to the sidewalls of the main member, and a top member having an outwardly extending flange overlying the flange of the bucket, said outwardly extending flange terminating in a downwardly extending flange surrounding the edge of the flange of the bucket, and sidewalls extending downwardly within and conforming to the sidewalls of the main member, the downwardly extending sidewalls of the top member terminating short of the upwardly extending sidewalls of the bottom member. 